Amazon.comOstensibly a study in the art of mostly vocal compositions based on the practice of hocketing, this excursion by Paul Hillier's Theatre of Voices goes well beyond a study of technique. It's a breathtaking glide through ancient music, to be sure, but it's also a fascinating look at how relatively late medievalists such as Guillaume de Machaut advanced musical processes documented in the Bamberg, Montpellier, Faenza, and Ivrea codices as well as in a variety of other collections. Hocketing is the process whereby multiple voices carry multiple parts simultaneously, with one voice extending beneath another, often providing a melodic backbone for improvisation. On Hillier's sonically peerless collection, you get almost ostentatious slipperiness on the low-register vocal in a 14th-century homage to St. Thomas (à Becket), and then you get a 13th-century piece from the Montpellier Codex in which a dizzying pair of upper-register voices sings in hockets while a lower-register chant continues beneath, almost viscerally piling polyphony. Hillier has excelled at what could have been an academic mission, and he's contributed a great deal to making the history of musical development poignantly beautiful. In addition, four organ solos fall into the sequencing of vocal tracks, allowing points of rest for the ear following the multitude of voices and thrilling keyboard examples, to boot. --Andrew Bartlett